Histological subtype of gastric adenocarcinoma: two cases of mixed fundic and pyloric mucosa-type adenocarcinoma

Adenocarcinomas with differentiation towards fundic or pyloric glands are rare histological subtypes. We herein describe two cases of new histological subtypes: mixed fundic and pyloric mucosa-type adenocarcinoma detected in Helicobacter pylori uninfected patients. The first patient was a woman in her 40s. A glossy, reddish, nodular lesion with a flat elevated whitish area was detected at the gastric fundus. When the nodular lesion was visualised with magnifying narrow-band imaging (M-NBI), an absent microvascular pattern plus an irregular microsurface pattern with a demarcation line was observed. The second patient was a woman in her 60s. A glossy, reddish, elevated lesion was detected at the gastric body. M-NBI finding was a regular microvascular pattern plus a regular microsurface pattern with a demarcation line. Histological examination of the resected specimens from both cases showed a very well- to well-differentiated adenocarcinoma which has differentiation towards the mixed fundic and pyloric mucosa. The histological and serological findings of both cases indicated the absence of H. pylori infection. The present two cases demonstrate further evidence of a new histological subtype of gastric adenocarcinoma: mixed fundic and pyloric mucosa-type adenocarcinoma, which has distinct characteristic endoscopic findings.